The invention relates to a mobile environment-controlled unit, such as an over-the-road compartment trailer, having an environmental-control system, such as a refrigeration unit, powered by an engine, which is started by battery power.
Transport refrigeration systems having an engine for powering the refrigeration unit can be operated in at least two modes of operation: continuous mode or cycle sentry mode. Continuous mode provides the benefit of a constant air flow through the compartment; however consumes more fuel than cycle sentry mode. Cycle sentry mode typically runs the refrigeration unit when the temperature of the compartment is not within a specified range or when critical system conditions exits that limits or prevents a restart of the engine. Critical system conditions that may force the engine to start or force the engine to stay on can be a low battery voltage or a low engine temperature. An example of a mobile environment-controlled unit having continuous and cycle sentry operation modes is a compartment trailer having a THERMO KING® transport temperature control unit with CYCLE-SENTRY™ protection.